Robot-assisted physical gait therapy is gaining recognition among the rehabilitation engineering community. Several robotic orthoses for the treatment of gait impairments have been developed during the last 2 decades, many of which are designed to provide physical therapy to a single joint of the lower limb; these are reviewed here. The mechanism design and actuation concepts for these single joint robotic orthoses are discussed. The control algorithms developed for these robotic orthoses, which include trajectory tracking control and assist-as-needed control, are described. Finally, the mechanism design and control of single joint robotic orthoses are discussed. There is a strong need to develop assist-as-needed control algorithms and to perform clinical evaluation of these robotic orthoses in order to establish their therapeutic efficacy.